Former Energy Secretary Steven Chu had pledged the solar panels would be in place at 1600 Pennsylvania Ave. by spring 2011. When that deadline came and went, administration officials blamed the government's competitive procurement process.

The U.S.-made solar panels being installed on the White House roof will convert sunlight directly into electricity to help power the Executive Mansion.

But this won't be the first time the White House has been powered by the sun. Former President Jimmy Carter first installed solar panels in the late 1970s, but they were removed seven years later during Ronald Reagan's administration.

It was not immediately clear whether the project will include a solar hot-water heater that was part of the plans announced in 2010.

Some environmentalists said they hope the move is a preview of more substantive policy changes to come.